It is very difficult to keep proboscis monkeys in captivity and few zoos have
been successful. However, with very careful husbandry, it is possible keep
proboscis monkeys in captivity and thus there is potential for ex situ
conservation (Agoramoorthy et al. 2004). Proboscis monkeys are particularly
threatened because one of their preferred habitats is coastal lowland forests,
locations which are also often preferentially developed or cultivated by people.
In sum, most of their habitat is threatened or already disturbed (Sebastian
2000). Compounding the problem, most proboscis monkeys are found outside of
protected reserves (Boonratana & Sharma 1992).

CONSERVATION THREATS

Threat: Human-Induced Habitat Loss and Degradation

As with many primate species, habitat loss is a major threat to proboscis
monkeys and much of their former habitat has already been lost (Bennett 1988;
Boonratana & Sharma 1992; Sebastian 2000). In addition, extensive proboscis
habitats are being targeted for development, as is the case in Central
Kalimantan, Indonesia (Meijaard & Nijman 2000a). Human land use, including
clearance for agriculture, plantation development (including for coca and oil
palm production), mining, for human resettlement and for industrial sites, as
well as burning, swamp reclamation, commercial aquaculture (fish and shrimp
farming), and logging destroys habitats and also isolates populations from one
another (Bennett 1988; Boonratana & Sharma 1992; Yeager 1992a; Sebastian
2000; Meijaard & Nijman 2000a; Soendjoto 2004; Agoramoorthy 2007). These
problems are also made worse by access roads, which fragment populations and
increases inbreeding (Soendjoto 2004). Also, many plantations have electric
fences around them, which may prevent normal proboscis monkey ranging
(Boonratana & Sharma 1992). Selective logging sometimes destroys preferred
sleeping and feeding trees (Yeager 1992a). After logging, forests are sometimes
poisoned to prevent undesirable vegetation from regrowing with the goal of
increasing timber productivity as the forest regenerates. This likely affects
proboscis monkeys adversely and prevents them from living in those habitats
(Bennett 1988). In addition, human immigration from other areas is increasing
land use and other sources of disturbance (Sebastian 2000).

Threat: Harvesting (hunting/gathering)

In some areas, proboscis monkeys are persecuted as crop raiders and are
poisoned. In some regions, they are hunted for food, and in others, they are
hunted recreationally, and as bait or feed for lizards, snakes and crocodiles
(Bennett et al. 1987; Bennett 1988; Boonratana & Sharma 1992; Meijaard &
Nijman 2000a; Soendjoto 2004). Hunting has already significantly reduced
proboscis monkey numbers at some localities (Meijaard & Nijman 2000a).
Also, even though they might not be the target species, firearm hunting of other
game has the potential to disturb proboscis monkeys and alter their behavior
(Tuen & Pandong 2007). However, hunting for food and persecution as crop
pests is not always the case, as local Muslim inhabitants will not eat monkey meat
for religious reasons (Boonratana & Sharma 1992). Proboscis monkeys are
also kept illegally as pets (Meijaard & Nijman 2000b). Their sleeping
habits near rivers also make them especially susceptible to hunting from boats
(Tuen & Pandong 2007).

Threat: Pollution

In riverine areas of increased human activity, pollution may increase,
especially due to spilled oil and fuel from boats, but also from human septic
waste (Yeager 1992a). All of these types of pollution have the potential to
alter proboscis monkey habitats.

Threat: Natural Disasters

Threat: Human Disturbance

Summertime activities of humans, such as fishing, fish-salting and smoking,
trapping, and encampments, all disturb proboscis monkeys, keeping them away from
preferred areas along rivers. Other activities that also disturb proboscis
monkeys include rattan collection, the collection of honey from bees, and
firewood gathering (Sebastian 1994 cited in Sebastian 2000). Further,
increasing boat traffic, sometimes as a result of gold extraction along rivers,
disturbs proboscis river crossing behavior and causes declines in population
density and group size. Also, increased boat traffic threatens proboscis
monkeys due to the potential for collisions while they are crossing rivers
(Yeager 1992a). In Sabah, some proboscis monkey populations are threatened by unmanaged tourism (Ramesh Boonratana pers comm.).

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